Protein is an essential nutrient found in almost every part of your body — including your bones, muscles, skin, hair, and nails. Protein keeps your bones and muscles strong. It makes up a molecule called hemoglobin, which carries oxygen throughout your body. It also makes up chemicals called enzymes, which cause the many reactions that keep your organs working.

You get protein from foods like red meat, chicken, fish, tofu, eggs, dairy, and nuts. You need to eat protein every day, because your body doesn’t store it.

Not enough protein in your diet

You can become deficient in protein if you don’t eat enough food sources — for example, if you follow a vegetarian or vegan diet. Severe protein deficiency is called kwashiorkor. This condition is more common in developing countries where people don’t have enough to eat.

Your body can’t properly absorb protein from the foods you eat

A problem absorbing protein from foods is called malabsorption. Possible causes include:

surgery, including weight loss surgery or procedures that remove part of your intestines

Liver damage

Your liver makes a protein called albumin, which makes up about 60 percent of the total protein in your blood. Albumin carries vitamins, hormones, and other substances throughout your body. It also prevents fluid from leaking out of your blood vessels (which is why fluid builds up in your body when you’re low in protein). Damage to your liver prevents it from making albumin.

Kidney damage

Your kidneys filter waste products from your blood. When your kidneys are damaged, wastes that should be filtered out remain in your blood. Substances like protein, which need to stay in your blood, leak into your urine. An excess of protein in your urine due to kidney damage is called proteinuria.

severe nausea and vomiting that prevents them from eating a normal diet

a vegetarian or vegan diet that’s low in protein

inability to afford to eat a well-balanced diet

During pregnancy, you need extra protein and other nutrients to supply both your own body and that of your growing baby. The Institute of Medicine (IOM) recommends that you get an extra 25 grams of protein daily starting in the second trimester of your pregnancy.

You can prevent hypoproteinemia by getting enough protein in your diet. The recommended daily allowance of protein (RDA) is 8 grams of protein for every 20 pounds of body weight. So if you weigh 140 pounds, you’ll need about 56 grams of protein daily. (This number can vary slightly based on your gender and activity level.)

If you’re vegetarian or vegan, eat more plant-based sources of protein, such as:

soy and almond milk

tofu

tempeh

beans

legumes (lentils, peas)

nuts (walnuts, almonds, pistachios)

nut butters

whole-grain bread

If you have a condition like liver disease, kidney disease, infection, celiac disease, or Crohn’s disease, follow your doctor’s recommended treatment. Getting treated will help improve your body’s ability to absorb protein and other nutrients from food.

Severe protein deficiency is rare in developed countries like the United States. However, you can get low in this important nutrient if you don’t get enough protein in your diet, or your body can’t properly absorb protein from the foods you eat. Work with your doctor and a dietitian to make sure you’re getting the right balance of nutrients in your diet.

Medically reviewed by Alana Biggers, MD on September 19, 2017 — Written by Stephanie Watson